The objective of this proposal is to acquire a three dimensional micro-computed tomography scanner. This system has the capability of digitizing the three dimensional architecture of biologic specimens at a resolution of between 20 and 40 microns. This system will provide necessary data for multiple investigators studying: the relationship between trabecular bone remodeling and applied stress, the relationship between bone architecture and its mechanical properties; the effects of mechanical, hormonal and drug therapies on the severity and incidence of osteoporosis; the patterns of calcification in atherosclerosis; and the interaction between degradation of articular cartilage and morphologic change subchondral trabecular bone in degenerative joint disease.